Rotary controls are used in a variety of communication devices to provide a user interface for controlling operational functions such as power on/off, volume, and channel change, to name a few. For certain rotary control applications, the control may be designed to provide tactile feedback in the form of “running-torque,” also referred to as frictional resistance, as the control is rotated.
The tactile feedback provided by a rotary control is particularly important for portable communication devices operating within a public safety environment. For example, in public safety environments involving fire rescue, paramedic and/or law enforcement, a handheld radio may be operated by a user wearing heavy gloves, working in an area with little or no illumination, and/or other environmental or physical conditions that necessitate a simple, easy to interpret user interface. Avoiding inadvertent actuation of the rotary control is also very important. As such, in the public safety environment, a communication device that offers a running-torque feedback is highly desirable. However, several design challenges are associated with the implementation of a running-torque rotary control. Life cycle sustainability is a concern. Past designs incorporating external torque adders have faced issues with tolerance sensitivity and over compression causing excessive wear. Stack up height, ease of manufacturability and knob retention are also factors taken into consideration in the design of a rotary control.
Accordingly, there is a need for an improved rotary control.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.